#include<map>
#include<set>
#include<cmath>
#include<queue>
#include<bitset>
#include<vector>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define rep(i,a,b) for(register int i = (a);i <= (b);++i)
#define per(i,a,b) for(register int i = (a);i >= (b);--i) 
#define mkp std::make_pair
typedef long long ll;
typedef unsigned long long ull;
using std::string;using std::cin;using std::cout;
const int N = 1e6+9;
const double eps = 1e-7;
int _,n,m;
double l,r,a[2*N],x,y,z,mid;

inline double f(double x){
    double ans = a[0] , p = x;
    rep(i,1,n) ans += a[i] * x , x *= p;
    return ans;
}

int main(){
    std::ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //freopen("in.in", "r", stdin);
    cin >> n >> l >> r;
    per(i,n,0) cin >> a[i];

    while(r-l > eps){
        mid = (l + r) * 0.5;
        x = f(0.5*(l+mid)) , y = f(mid) , z = f(0.5*(mid+r));
        if(y >= x && y >= z){
            l = 0.5*(l+mid) , r = 0.5*(mid+r);
            continue;
        } else if(x <= y && y <= z){
            l = mid;
            continue;
        } else {
            r = mid;
            continue;
        }
    }
    
    printf("%.5lf\n",mid);
    
    return 0;
}